CaCO3 whisker modified Engineered Cementitious Composite with local ingredients

Abstract

This paper aims at developing CaCO3 whisker modified ECC with local ingredients in China. CaCO3 whisker is a kind of micro scale fibrous material (inorganic single crystal) with a diameter of 0.5–2μm and an aspect ratio of 20–60. It has a high tensile strength of 3–6GPa and high elastic modulus of 410–710GPa. Therefore, CaCO3 whisker can potentially reinforce the ECC materials at microscopic level. In this study, cube compressive and uniaxial tensile tests were conducted to investigate the influence of CaCO3 whisker on ECC’s mechanical properties. The experimental results indicated that incorporating CaCO3 whisker can improve compressive strength and tensile strain-hardening behavior (especially tensile strain capacity). When CaCO3 whisker was added at the optimal content of 0.5% by volume of total ECC mixture, the compressive strength of composite increased from 23MPa to 30MPa, and the ultimate tensile strength and tensile strain capacity increased by 53% and 114%, respectively. Addition of CaCO3 whisker can also enhance the robustness of ECC mixtures. The coefficient of variation of mechanical properties was found to be reduced by 90% compared to that of the ECC without CaCO3 whisker. In addition, when CaCO3 whisker is added, fly ash content has negligible influence on ultimate tensile strength of the composite, which suggests that the frictional bond strength of fiber/matrix interface is significantly affected by CaCO3 whisker.